1. Field of the Invention
The present invention relates to an inkjet printing head substrate and an inkjet printing head using the substrate.
2. Description of the Related Art
As inkjet printing heads used for inkjet printing apparatuses, inkjet printing heads in which ink drops to be ejected are formed by various systems have been known. Among those, an inkjet printing head utilizing heat as energy for ejecting ink can be made into a high-density multi-nozzle printing head with relative ease, and the inkjet printing head is capable of performing high-resolution, high image quality, and high-speed printing.
In order to store information specific to the printing head such as an ID (Identity) code of the printing head itself and a driving characteristic of an ink ejecting mechanism so as to be freely read out in such a printing head, a ROM (Read Only Memory) is installed in the base body of the printing head in some cases. This function is a means extremely useful for performing optimum driving by obtaining information specific to the printing head in printing when an inkjet printing head detachable from an inkjet printing apparatus main body is used. For example, there is disclosed in Japanese Patent Laid-Open No. H3-126560 that an EEPROM (Electrically Erasable Programmable ROM) is installed in a printing head. In accordance with this method, relatively large volumes of data can be stored in the EEPROM.
Further, a technique has been known in which resistance denoting information specific to the head is formed along with a layered film having an ink ejecting mechanism and the like on an inkjet printing head substrate. This technique is useful for a case of a relatively small volume of information. Because the information specific to the inkjet printing head can be obtained when the inkjet printing apparatus reads out a value of the resistance formed in the printing head substrate, it is possible to perform optimum driving for ejecting ink.
Further, there is disclosed in Japanese Patent Publication No. 3428683 that fuses which will be a ROM are formed at the same time of forming a layered film having an ink ejecting mechanism and the like in a base substrate for manufacturing the inkjet printing head substrate. By selectively carrying out fusion cutting of the fuses by controlling a logic circuit formed at the same time of forming the fuses, a state as if the fuses hold binary data can be made according to cutting or non-cutting of fuses.
With respect to such a printing head having a ROM on the printing head substrate, because there is no need to prepare a ROM chip separately from the printing head substrate, the structure thereof is not complicated, and the productivity is satisfactory, and it is possible to accomplish the reduction in size and weight thereof.
However, in inkjet printing heads capable of storing individual information as described above, there are the following problems.
A printing head in which the ROM chip is installed at the outside of the inkjet printing head substrate (hereinafter referred also to as abase substrate) is capable of storing large volumes of data, but is unfavorable for productivity improvement or reduction in size and weight thereof.
Further, when the ROM (hereinafter also referred to as fuses) is provided on the base substrate, the printing head is useful for productivity improvement or reduction in size and weight thereof, but is not suitable for storing a large volume of information. Accordingly, in order to store a large volume of information required for performing high image quality printing, it is necessary to arrange many fuses on the base substrate. Further, in accordance with the arrangement of the fuses, in order to carry out fusion cutting and readout of the fuses, it is necessary to arrange a drive element transistor having the driving ability capable of carrying out fusion cutting of the fuses, and a logic circuit such as a shift register to select a fuse.
In recent years, in order to accomplish high image quality in printing, circuits in base substrates have been made in high density, and further, the base substrates are minimized in size in order to keep the manufacturing costs down. In such a situation, it is difficult to arrange many fuses, drive element transistors, logic circuits, and the like in the base substrate in order to store a large volume of information.